Off-highway vehicles, such as, for example, track type tractors, track loaders, wheel loaders, motor graders, etc., are used to perform many different earthmoving tasks. In order to effectively perform these tasks, these vehicles require a power source and drive train that provide significant power to the ground over a range of operating conditions. The power source may be an engine such as, for example, a diesel engine, a gasoline engine, a natural gas engine, etc., that generates a power output. The drive train for a typical off-highway vehicle generally includes a transmission and a final drive.
The transmission may be connected to the engine via a torque converter, and converts the power output from the engine to useful power by controlling torque, speed and direction. The transmission may be a hydraulically-controlled planetary design that includes planetary gear sets and hydraulic clutches that allow the vehicle to work at different speeds while keeping the engine within a desired operating range. The final drive may be coupled to the transmission via a differential, and applies the driving force to the tracks or wheels. Rotating hydraulic clutches for planetary transmissions are located between the planetary gear trains to which they are coupled, which increases axial length, number of parts, complexity and cost.
One known planetary gear set for an automobile automatic transmission includes an inner sun gear, an outer sun gear (ring gear) and three planetary gears which are mounted in a planetary gear carrier using roller bearings and three planetary gear bolts, each of which includes axial and radial bores to supply lubrication oil to the planetary gears (US 2009/0253545 A1). The rear plate of the planetary gear carrier is connected to an outer disk carrier of a clutch of a shift element, while both the front and rear plates include pressure oil ducts and through-bores, respectively, to supply pressurized oil to the clutch piston. A sturdier, more compact and more efficient design is desirable, i.e., one that reduces axial length, number of parts, complexity, cost, etc.